When you do your funding round, ideally you'll want to have at least 100,000 shares in issue, so you can have a nice low price per share and fine-grained share allocation in your new round. For example, if you only have 100 shares in total and you're creating 17 new shares in your first funding round, your price per share would be thousands of pounds, meaning investors could only invest multiples of that amount (you can't have fractional shares).
However, when you incorporate, the minimum nominal value for each share is £0.01.
So - ideally create 100 shares, split amongst the founder(s) as you'd like, at a price per share of £0.01, for a total paid-up share capital of £1.
Then, use SeedLegals to do your Share Split later. (Check out this article on how to do this in just a few minutes.)
Once you have a company bank account, you'll need to actually write a cheque or do a bank transfer to pay for those shares - don't forget to do that!